docs: def set_circulating(self, param):
          """
          Sets whether to circulate - in effect whether the heater is on.
  
          :param param: The mode to set, must be 0 or 1.
          :return: Empty string.
          """
          if param == 0:
              self.is_circulating = param
              self.circulate_commanded = False
          elif param == 1:
              self.is_circulating = param
              self.circulate_commanded = True
          return ""